Psyllids are small phloem feeding insects that typically feed on either a single plant, or a few related plants. They can serve as vectors for different microbial species that can act as plant pests. They are also suspected of delivering toxins to plant species as they feed, causing pathogenesis.
The citrus psyllids from Asia, Africa, and America are small insect pests that feed on the leaves and stems of citrus trees. These psyllids transmit a bacterial disease called Huanglongbing (HLB), also known as citrus greening disease. All citrus and closely-related species are susceptible hosts for both citrus psyllid insects and HLB disease. This bacterial disease is transmitted to healthy trees by the psyllid after it feeds on infected plant tissue. Once a citrus tree is infected with HLB, there is no cure and the plant will eventually die. The best way presently to prevent the disease from killing citrus trees is to stop these citrus psyllids.
The potato/tomato psyllid, Bactericera cockerelli, has been a longstanding pest of solanaceous crops, including potatoes, tomatoes, peppers, and eggplants. It can damage plants through direct feeding, is suspected of delivering a plant toxin, and also transmits the bacterial pathogens Liberibacter psyllaurous and Liberibacter solanacearum. In potatoes, it is thought to cause a systemic disease called psyllid yellows that includes a reduction in growth, yellowing of leaves, erectness of new foliage, leaf abnormalities, shortened and thickened internodes, enlarged nodes, aerial tubers, premature senescence and early plant death. In tomatoes, the foliage symptoms are similar to that of potatoes, and fruit set, size, texture, and yield can be decreased. B. cockerelli and the transmission of L. solanacearum has also been linked to zebra chip disease in potatoes, which causes stunting, chlorosis, swollen internodes of the upper growth, proliferation of axillary buds, aerial tubers, browning of the vascular system, leaf scorching, and premature plant death. Different insecticides have been used against B. cockerelli, however, recently some resistance to common treatments has been detected in psyllid populations in California (Butler and Trumble, Terrestrial Arthropod Reviews, 5, 87-111, 2012).
No control method is currently available that will eliminate psyllids and the risk of pathogen transmission within a citrus grove or field of solanaceous crops. Methods to suppress psyllid infestation will likely slow the spread of the disease and maintain the economic feasibility of crop production.
It is in view of these issues that the invention described herein was developed.